Operating mechanism for switches



Aug. 31, s DURBIN OPERATING MECHANISM FOR SWITCHES Filed Oct. 28, 1941 III II I 50 lNVENTOR 8739/1 45) Ii DORE/N r /9 52 wzz fgi I ATTO NEYJ.

Patented Aug. 31, 1943 2,328,266 OPERATING MECHANISM FOR SWITCHES Stanley H. Durbin, Brooklyn, N.

E. W. Bliss Company, poration of Delaware Y.. assllnor to Brooklyn, N. Y., a cor- Application October 2a, 1941, Serial No. 416,801 8 Claims. (01. 200-47) The present invention relates to improvements in operating mechanisms for switches and more particularly operating mechanisms for switches used for controlling a part or parts of a machine and adapted to be operated by engagement or disengagement, or other coaction with some moving part of the machine so that the controlled part or parts will operate in the desired manner.

An important object of the invention is the provision of improved means for eifecting positive transmission of movement, resulting from such coaction, to operate an actuating member of the switch.

Another important object of the invention is the provision of means, substantially independent of the operation of the switch, for yieldably holding, in inoperative position, the several movable parts of the device which move the switch-actu I ating member. The use of the expression inoperative position here and elsewhere in this specification and in the accompanying claims refers to conditions wherein the switch employed in the device is unafiected by the movable parts of the device.

It is also an object of the invention to provide a switch-operating mechanism which may respond to very slight movement of the part of the machine which causes operation of the switch.

Still another object of the invention is the provision of a simple switch-operating mechanism which will be inexpensive to produce, dependable in operation and subject to a minimum of wear.

These and other objects and advantages will be apparent from the following description and the accompanying drawing, in which:

Figur 1 is a top plan view of a preferred embodiment of the invention, a cover being removed to show the mechanism.

Fig. 2 is a central vertical section substantially on the line 22 of Fig. 1.

Fig. 3 is a horizontal section substantially on the line 3-3 of Fig. 2. I

Fig. 4 is a horizontal section substantially on the line 4-4 of Fig. 2.

Fig. 5 is an enlarged fragmentary view of a portion of Fig. 4.

In the embodiment illustrated in the drawings, an electric switch II is employed of the type through the medium of which an electric circuit may be established, broken, shifted or reversed, or otherwise changed, as may be desired in the machine in which th switch is employed, by a very slight movement of a plunger I2 or other switch-actuating member. 'I'he'switch referred employed in the embodiment shown in the drawings which is used, of course, only for illustrative purposes and not to limit the invention in any way.

The switch I I may b provided with a suitable number of terminals I3, depending upon the nature of circuit control intended to be exerted by said switch.

By means of screws I4, the switch II may be I fixed to base plate I5 of a box I6 of metal or other suitabl material, within which most of the operating mechanism is enclosed. In addition to the said base plate, the box I6 may comprise sides Il, one of which may be provided with a threaded opening I8 to which a suitable electric-wire conduit may be attached and through which electric wires from within said conduit may pass into the interior of the box I6 and be connected in any conventional manner to the terminals I3. The interior of the said box may be lined'with any suitable insulation material, indicated generally as I9.

Although the mechanism performs two main functions, namely, the actuation of the switch I I and the automatic returning of all parts to inoperative positions after each operation, the said two functions, however, are performed substantially independently of each other in the sense that the portions of the mechanism which actuate the switch are only indirectly related to the portions thereof which return the parts to inoperative positions, and likewise the portions of the mechanism which serve to return the parts to inoperative positions are only indirectly related .to the switch-actuating portions of the mechanism. This independence in the functioning of the mechanism yields certain advantages which will more fully hereinafter appear.

Referring first to the switch actuating portions of the mechanism; a trip-lever 20 having a bifurcated free end 2| and a roller 22 suitably mounted between the two end portions of the latter may be fixed in any one of many radial positions upon the outer end of a lever shaft 23,

the lower end of which as viewed in Fig. 2, is carried within a bushing 24 fixed in the base plate It, and the upper end of said shaft may extend through a suitable bushing 25 fixed in a bearing plate 28 which is suitably fastened to the top of the box It, as by screws 21.

The inner end of the lever may be in the form of a slightly resilient split collar 28 of a conventional type extending about the upper end of the shaft 2- The said collar may be provided'with a clamping screw or bolt 29, which, when loosened, may permit the lever 20 to be 9, disc 36a which is restrained against movement moved to any radial position without turning the shaft 23, and which, when tightened, may secure the lever firmly in any desired radial position upon said shaft so that the latter and said lever will be constrained to turn together. Although the lever may in the manner described be fixed upon the shaft in any number of available positions, it has been considered sufficient to indicate, in Fig. 1, one of the positions in which said lever may be fixed upon the shaft 23, and in Fig. 2 another possible position thereof,

A substantially cylindrical cam 38 is fixed upon the shaft 23 toward the lower end thereof and constrained to rotate therewith. The said cam has a fiat 39 on the side thereof nearest the switch i i. A substantially flat motion transmitting element in the form of a flat bar 32 is disposed between the cam 38 and the plunger H of the switch ii. The said bar may be provided with a recess 33 adapted to receive the outer end of the plunger i2 and one end of the bar 32 may set quite loosely within a socket 36 provided in a boss 35 formed on the inside of one of the sides ll of the switch box. The shaft 23, it will be seen, is perpendicular to the plunger i2 and the parts just referred to are arranged as best understood from Fig. 3 so that when they are in inoperative positions the outer .end of the plunger i2 will set within the recess 33 of the bar 32. and the flat side of the latter which is farthest from the switch M will be in intimate juxtaposition to the flat 3i of the cam so.

Bearing in mind that a movement of about 0.001 of plunger i2 will operate the switch M, it will be seen that a very slight rotation of the cam 3!? will operate to press the plate 32 toward the left as viewed in Fig. 4, and in consequence press the plunger i2 sufliciently to operate the switch. With the parts proportioned as shown in the drawing, it will be seen that the said switch may be operated by a rotation of the shaft 23 of approximately two degrees in either direction from its inoperative position as indicated by the radial lines shown in Fig. 4 extending to the right from the axis of said shaft.

Although as hereinbefore explained, the switch ill is adapted to operate as a result of a very flight inward movement of the plunger i2, it should be observed that, if only such slight movement of the plunger i2 were provided for, it would be very diflicult indeed to mount the box it in a machine so that the moving parts thereof which actuate the lever 29 would move the inwardly further than necessary to operate the toward the inner end of said plunger by an annular shoulder in within the latter. One end of a pin 3!, which is guided within a portion of the cavity in the plunger I2, engages the disc 36a. and upon the other end of said pin is fixedly mounted a button 38 which is adapted to press upon and actuate a contact member 39 within the switch ii. The said contact member at the point where the button 38 engages it is constrained to very limited movement in the operation of the switch, the movement thereof being approximately 0.001. Due to its shape and resilient characteristics the said contact member must be pressed and held pressed by the button 38 in one of its operative positions and when relieved of the force exerted thereon through said button it will return to its other or normal operative position.

The characteristics of the compression coil- I spring 38 are such that it will not yield to any In order to obextent, beyond the initial compression given to it in the assembling of the device, except upon the application thereto through the medium of the plunger it of a force substantially in excess of the force required to be applied to the contact member 39 in order to operate the switch; hence, in actual operation of the switch, the plunger G2, the spring 3%, the pin Si and the button 3% constitute, to all intents and purposes, a rigid switch-actuating assembly, However, after the said enumerated elements constituting the switch-actuating assembly have been moved inwardly suiiiciently to operate the switch ii, the button 2 38 and the pin 31 are estrained against further inward movement by the substantial inc apability of the contact member 39 to move any further. The plunger 92, however,- may move further inwardly without affecting the operation of the contact portions of the switch it upon application thereto of a force suficient to cause the coil-spring 3b to become further compressed. This further movement of the plunger M will be hereinafter referred to as overtravel of said plunger. The overtravel, according to the design oi the parts of the rigid switch-actuating assembly may, of course, vary, but for all practical purposes it is sufficient if such overtravel in the illustrated embodiment be approximately /8".

Referring now preferably to Fig. 4, it should be noted that the difierence between the radius of the cam 3b and the shaft 23 at the center of the fiat 3i and the radius thereof at the circular portion of the periphery of the cam is no more, and preferably is slightly less than, the overtravel of the plunger i2, so that although a rotation of the cam 38 of as little as approximately 2 may sufiice to operate the contacts in the switch ii, the lever 2% may, nevertheless, be turned very substantially beyond the said 2 because of the overtravel provided for in the switchactuating assembly. Thus, considerable latitude may be availed of in placing and adjusting the switch and its operating mechanism in a machine. The switch and its operating mechanism should preferably be so disposed that in the operation of the machine in which it is employed, the maximum swing of the lever in either direction from its inoperative position is preferably somewhat less than 90. This preferred condition, however, introduces no difficulties in utilizing the invention.

Referring to the means for yieldably holding the cam and the parts connected therewith in inoperative positions, there is preferably provided a fork which, as bestseen in Fig. 3, has two arms 4|, 4|, extending about'and substantially in engagement with opposite sides of an enlarged portion 42 of the shaft 23. The fork 40 is fixedly carried upon one end of a fork rod 43 which is guided within a tubular rod guide 44 having a reduced closed end 45 resting within a socket 46 formed in a boss 41 on the inside of one of the sides I! of the switch box. Because of the close proximity of the guide 44 to the terminals 3, the' said guide may preferably be formed of insulating material such, for example.

' as a suitable fibrous composition pressed to the desired substantially rigid form. The said guide 44 has a cylindrical cavity 48 within which the free end of the fork rod 43 is accurately fitted and adapted to reciprocate. The outer end of the cavity 48 is enlarged sufficiently to accommodate a compression coil-spring 49 which is disposed about the fork rod 43 and has its one end in engagement with a shoulder 50 in the cavity 48 and its other end in engagement with the fork 40.

The free ends of the arms 4|, 4| engage cam pins 5| fixed in and extending upwardly from the cam 30 as viewed in Fig. 2. The centers of both said cam pins are preferably in a plane extending parallel to the plane of the flat 3|, preferably on the side of said cam opposite to said flat.

It will be seen thatthe' spring 49, being under compression, functions to urge the fork 40, and more particularly the arms 4|, 4|, thereof, into engagement with the pins 5| so that, except when the cam 30 is subjected to a force tending to turn it from its inoperative position indicated in Figs. 1, 2 and 3, the flat 3| will lie in intimate relationship to the adjacent fiat side of the bar 32, in which position th plunger |2 of the switch II will be unaffected by the described operating mechanism. It will also be seen that if the lever 20, through coaction with some moving part of the machine in which the device is incorporated has been rotated through an angle of somewhat less than 90 to correspondingly turn the cam 30 to the same extent from its position as indicated in Figs. 1, 2 and 3, the said lever when disengaged by such moving part and the cam 30 controlled by said lever, will return to their inoperative positions as indicated in Figs. 1, 2 and 3, as a result of the action of the fork 40 upon one Or the other of the cam pins 5| in response to the compressive force of the spring From the foregoing it will be perceived that the positive coaction of the various moving parts of the disclosed switch-operating mechanism with the plunger I2 of the switch occurs quite independently of the operation of the spring-actuated means for returning and holding the moving parts of the mechanism normally in inoperative positions. 'Thus the advantages available in the use of spring means for the last stated purpose are availed of without deriving the disadvantages which. would be inherent in the use of spring means in the moving parts which operate the plunger of the switch. a

' In practice, the type of switch II to be used would depend upon the nature of the electric circuit required to yield a desired result in a machine in which the invention is employed. The said switch, for example, might be normally open and adapted to be closed by the pressing of the plunger I2, or might be normally closed and adapted to be opened by the pressing of said plunger; or the switch might be one adapted to shift a circuit from one wire or lead to another when the said plunger is pressed or otherwise modify the circuit in which it is employed.

When a moving part of the machine coacts with the roller 22 in a manner which may rotate the lever 20 to an extent somewhere between approximately 2 and somewhat less than the said lever during the first portion of its movement, that is, through approximately 2, will turn the cam 30 with it and through the resultant displacement of the bar 32 as shown in Fig. 4 will press the plunger |2 inwardly suificiently to actuate the'switch to yield the desired operation of a controlled portion of the machine. Continued rotation of the lever 20 will cause the bar 32 to ride upon the circular portion of the periphery of the cam 30, but the additional movement of the bar 32 occasioned by thecontinued rotation of the lever 20 will be transmitted to the plunger |2 only within the overtravel'of the latter and, hence, will give rise to no change in the operation of the switch or the machine. After the moving part of the machine passes beyond or otherwise ceases coaction With the roller 22, the lever 20 and the cam 30 are returned to their inoperative positions shown in Figs. 1, 2 and 3, by the action of the spring 49 and the fork 40, thus permitting the plunger |2 to move outwardly to restore the switch to its normal operative position and leaving the device in readiness for further operation in the control of the machine.

It should be understood that the embodiment described herein and illustrated in the accompanying drawing is employed solely for the purpose of illustration and not by way of limitation of the invention. The inventive concept could obviously be employed in various ways without departing from the'spirit of the invention as defined in the following claims.

What I claim is:

1. An operating mechanism for a switch having a reciprocable actuating member, said mechanism comprising a substantially non-flexible motiontransmitting element having a portion restrained against substantial movement laterally of the line of movement of said actuating member and adapted to engage and operatively move the said member, a cam disposed adjacent said element and adapted, when turned from an inoperative to an operative position, to engage and move the latter and, through the movement of th latter, to move said actuating member whereby to operate the switch, yieldable means, independent of the switch and its said actuating member and in constant engagement with said cam whereby to.

urge the latter normally to an inoperative position and means, responsive to movement of a part of a machine in which said mechanism is employed, for turning said cam from aninoperative to an operative position against the urging of said yieldable means.

2. A mechanism according to claim 1, further characterized in that a first part of the movement of the said reciprocable actuating member in one direction operates the switch and a further part of such movement thereof constitutes overtravel, and also in that the said cam has a flat and adjacent circular peripheral portions, the said cam being in inoperative position when said fiat is in intimate relationship with said motion-transmitting element, and the radii of said cam at said circular peripheral portions being such that the coaction of the latter with the said element causes such further movement of the switch-actuating member only within the limits of such overtravel.

3. In combination, a switch having an actuating plunger a first part of the movement of which operates the, switch and a further part of the movement of which constitutes overtravel, and an operating mechanism for said switch, said mechanism comprising a mounting member to which the said switch is fixed, a shaft journaled in said mounting member, a cam mounted upon and constrained to rotate with said shaft and having a fiat on a working portion of the periphery thereof, the working portions of said periphery otherwise being. substantially circular, a substantially rigid elongated bar pivotally retained toward one end thereof upon said mounting member, the said bar extending between the plunger and the cam substantially perpendicularly with respect to the axis of said plunger and being in engagement, on one side thereof toward its other end, with the free end of said plunger and having a fiat on its opposite side in engagement with the said hat on the cam when the latter is in inoperative posi tion, the radii of said cam at'said circula peripheral working portions being such that the co-.

action of the latter with the said bar causes such further movement of the plunger only within the limits of such overtravel, the mechanism including also means, responsive to movement of a part of a machine in which the mechanism is used, for turning said cam.

4. In a switch-operating mechanism having a cam adapted for rotation from an inoperative to an operative position to actuate the switch, means for yieldably holding said cam in such inoperative position, said means comprising a pair of pins both fixed in said cam toward one side of the axis thereof and equidistant from said axis, a fork having similar rigid arms connected together against movement relatively to each other and extending about opposite sides of said axis and having their free ends in engagement with both said pins when the parts of the said mechanism are in inoperative positions, and spring means for urging said fork into and yieldably holding it in contact with both said pins, the said fork being substantially constrained to reciprocating movement perpendicularly to a straight line which passes through both said pins when the cam is in its inoperative position.

5. In a switch-operating mechanism having a cam adapted to rotate between an inoperative and operative positions in actuating the switch, means according to claim 4 further characterized in having a fork rod fixed to said fork, means for guiding said rod and fork whereby to confine the latter to its said reciprocating movement, and the said spring means comprising a compression coilspring extending about said rod with one end fixed relatively to the axis of thecam and the other end pressing against said fork whereby to urge said fork into and yieldably hold it in contact with both said pins.

6. Operating mechanism for a switch having a reciprocable actuating member, said mechanism comprising a housing to which the said switch is rigidly secured, a cam shaft and a cam thereon rotatably mounted in said housing, means coacting with said cam shaft whereby to rotate the latter and said cam, a motion transmittin element disposed between and adjacent to said switch-actuating member and said cam and constrained to movement wherein the portion thereof adjacent to said actuating member moves substantially in line with the operating movement of the latter, the said cam having a fiat and the mechanism including means for yieldably holding the cam against rotation in such position that the said flat is substantially perpendicular to the line of operating movement of said switch-actuating member and is in position to coact with an adjacent fiat surface of said motion transmitting element when the cam is turned, whereby to cause said element to establish operating movement in said switch-actuating member; the said cam holding means comprising a pair of pins both fixed in said cam toward one side of the axis thereof and equidistant from said axis, a yoke having a pair of similar arms extending about opposite sides of said cam shaft with their free ends in engagement with both said pins when the parts of said mechanism are in inoperative positions, and spring means for urging said fork into arigisyield'ably holding it in contact with both said p '7. In a switch-operating mechanism, means according to claim 4, further characterized in that the said spring means is in engagement with said fork upon only a single area of a surface thereof.

8. In a, switch-operating mechanism, means according to slaim 4, further characterized in that the said spring means comprises a single spring which is in engagement with said fork upon only a single area of a surface thereof.

STANLEY H. DURBIN. 

